HttpParams interface represents a collection of immutable values that define
a runtime behavior of a component. HTTP parameters should be simple objects:
integers, doubles, strings, collections and objects that remain immutable
at runtime. HttpParams is expected to be used in 'write once - read many' mode.
Once initialized, HTTP parameters are not expected to mutate in
the course of HTTP message processing.

The purpose of this interface is to define a behavior of other components.
Usually each complex component has its own HTTP parameter collection.

Instances of this interface can be linked together to form a hierarchy.
In the simplest form one set of parameters can use content of another one
to obtain default values of parameters not present in the local set.